This invention relates to an automated control for a guidance system in order to control operation of a guidance control system.
Guidance systems frequently are used to assist an operator in guiding an agricultural implement in the field. Basically, the guidance system uses some type of sensing means, such as sensing wands, which sense the position of the crop relative to the implement. The guidance system also has a guidance mechanism which adjusts the position of the implement relative to the tractor so that the position of the implement corresponds to the position of the crop. The guidance function can be performed in many ways, but may be performed by adjusting the angle of the implement relative to the longitudinal axis or direction of travel of the agricultural tractor. While the implement is travelling through the field, the position of the crop relative to the implement will change. In order to correct this deviation, the guidance system will adjust the angle of the implement relative to the tractor.
Many agricultural tractors have a three-point hitch system located at the rear of the tractor. The three-point hitch is designed to connect an implement to the tractor and permit the tractor to raise and lower the implement. In normal operation, the operator lowers the implement in order to effect the specific agricultural operation. When the operator reaches the end of the field, he normally raises the implement and turns the vehicle so that he can begin the next pass down the field. After turning the vehicle at the end of the field, the operator then lowers the implement to begin the next pass down the field.
When the operator is using a guidance system and reaches the end of the field, the operator raises the implement and switches the guidance system to the manual mode which can position the implement into a center position behind the vehicle. If the operator does not switch the guidance system, the guidance mechanism usually causes the implement to move relative to the tractor due to the swaying of the wands as the tractor is turned at the end of the field. In addition, it is advantageous for the guidance mechanism to be centered when starting the next pass down the field. After the operator has turned the tractor and the implement, the operator lowers the implement. The operator then manually switches the guidance system to the automatic mode for the next pass through the field.
A problem is that it is inconvenient for the operator to switch the guidance system when the operator is turning the tractor at the end of the field. The operator is performing many tasks when the operator is turning at the end of the field, such as, moving hydraulic levers, turning the steering wheel, aligning the tractor and implement for the next pass down the field, watching for obstacles and avoiding the fence at the end of the field. Thus, the operator is performing many tasks and the turning operation would be simpler, easier, and more convenient if the operator did not need to manually switch the guidance system.
Another problem is that the operator may forget to switch the guidance system to the manual mode when the operator reaches the end of the field. When the operator raises the implement and turns the tractor and implement combination, the sensing means or sensing wands will swing or move due to the rough field conditions at the end of the field. This movement of the sensing wands will cause the guidance mechanism to move in response to the movement of the sensing wands. Furthermore, this movement of the guidance mechanism and the implement reduces the stability of the tractor during the turn. This unnecessary movement of the hitch mechanism can cause premature wear in the hitch mechanism and could possibly damage the hitch mechanism.
Another problem which may occur is when the operator fails to switch the guidance system when the operator begins the next pass down the field after completing the turn at the end of the field. For example, the operator may remember to switch the guidance system to the manual mode before beginning the turn at the end of the field. However, after completing the turn, the operator may forget to switch the guidance system to the automatic mode. Therefore, the operator will lower the implement and begin the agricultural operation without the benefit of the guidance system. Consequently, if the operator is using the guidance system with a cultivator, the cultivator may destroy portions of the crop rows before the operator discovers that the guidance system is not in the automatic mode. In addition, if the operator is using the guidance system with a planter, the operator may not achieve the correct spacing of the rows with respect to previous sets of rows. This improper spacing of the rows can result in further complications during cultivation or harvesting.
An additional reason for switching the guidance system from the automatic mode to the manual mode at the end of the field is to equalize or center the hitch mechanism. The guidance system will operate more efficiently if the hitch mechanism is in the center position when the operator begins the next pass down the field. When the hitch mechanism is in the center position, the implement is parallel to the hitch system of the tractor. By having the hitch mechanism in the center position when the operator begins a pass down the field, the guidance mechanism is able to use the complete freedom of movement of the guidance mechanism. If the guidance mechanism is not in the center position when beginning a pass down the field, the hitch mechanism may be limited in its ability to make corrections due to a predisposition of the hitch mechanism.
In one guidance system which is presently available, the sensing mechanism contains a micro-switch to automatically switch the control system. In this design, the micro-switch is located in the sensing wand assembly. When the implement and the attached wand assembly are raised, the sensing wands rotate downwards due to gravity and depress the micro-switch. When the micro-switch is depressed, a signal is sent to the control box which switches the guidance system to center the guidance mechanism. When the implement is lowered, the sensing wands engage the ground and the micro-switch is released.
This micro-switch design has several problems. First, the switch assembly is located near the ground and it subject to contamination by dirt and other debris which would cause the micro-switch to malfunction Second, the micro-switch assembly could malfunction if debris, such as crop residue, interferes with the plunger or contact arm on the micro-switch.
Third, this micro-switch assembly requires that the sensing wands contact the ground in order for the micro-switch assembly to function properly. However, some sensing assemblies only contact the crops and not the ground in order to sense the position of the crop row. Sensing assemblies which only sense the position of the crops are more sensitive and more accurately sense the position of the crop row. Therefore, a micro-switch assembly cannot be used on sensing assemblies which only sense the crops because these sensing assemblies normally do not contact the ground Since the micro-switch relies upon contact with the ground in order to function, the micro-switch cannot be used with sensing assemblies which do not contact the ground
Finally, when the micro-switch assembly is located in the sensing assembly, it is difficult an tedious to adjust the micro-switch assembly so that it activates and deactivates the control system at the appropriate position.